These are benign, meaning not cancerous. Fewer than half of lumps and bumps you find on a dog are malignant, or cancerous. Still, they can look the same from the outside, so it’s hard to tell.

white substance comes out. Abscess: This is a buildup of pus under the skin. It can be caused by an infection or an insect bite. Mast Cell Tumor: This is the most common skin cancer found in dogs.